Protein macroarray identification of biomarkers in HER2-positive breast cancer.

e11575 Background: The holy grail of breast cancer diagnosis and management is the identification of biomarkers that can simplify diagnosis, predict response to treatment and facilitate follow-up to detect early recurrence and metastasis. We set out to identify autoantibodies in the serum of HER2-overexpressing breast cancer patients using protein macroarrays. Methods: We utilized a PEX protein macroarray comprising a human protein expression library containing 16,000 antigens to proteins known to be involved in tumorigenesis, dissemination and recurrence. Preoperative blood was collected from fifteen matched patients in three groups: HER2-positive, HER2-negative and non-cancer controls. Clinicopathological characteristics were prospectively obtained. Results: The macroarray uncovered 1,186 autoantibody-antigen interactions in breast cancer patient’s sera. Comparative analysis identified only seven common to three HER2-positive patients and forty-nine proteins common to two patients. No antibodies were ex...